/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Collection;
import java.util.Comparator;
import java.util.Map;
import java.util.Set;
import java.util.SortedSet;
import javax.annotation.Nullable;

/**
 * A {@code SetMultimap} whose set of values for a given key are kept sorted; that is, they comprise
 * a {@link SortedSet}. It cannot hold duplicate key-value pairs; adding a key-value pair that's
 * already in the multimap has no effect. This interface does not specify the ordering of the
 * multimap's keys. See the {@link Multimap} documentation for information common to all multimaps.
 *
 * <p>
 * The {@link #get}, {@link #removeAll}, and {@link #replaceValues} methods each return a
 * {@link SortedSet} of values, while {@link Multimap#entries()} returns a {@link Set} of map
 * entries. Though the method signature doesn't say so explicitly, the map returned by
 * {@link #asMap} has {@code SortedSet} values.
 *
 * <p>
 * See the Guava User Guide article on
 * <a href= "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">
 * {@code Multimap}</a>.
 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
    // Following Javadoc copied from Multimap.

    /**
     * Returns a collection view of all values associated with a key. If no mappings in the multimap
     * have the provided key, an empty collection is returned.
     *
     * <p>
     * Changes to the returned collection will update the underlying multimap, and vice versa.
     *
     * <p>
     * Because a {@code SortedSetMultimap} has unique sorted values for a given key, this method
     * returns a {@link SortedSet}, instead of the {@link java.util.Collection} specified in the
     * {@link Multimap} interface.
     */
    @Override
    SortedSet<V> get(@Nullable K key);

    /**
     * Removes all values associated with a given key.
     *
     * <p>
     * Because a {@code SortedSetMultimap} has unique sorted values for a given key, this method
     * returns a {@link SortedSet}, instead of the {@link java.util.Collection} specified in the
     * {@link Multimap} interface.
     */
    @CanIgnoreReturnValue
    @Override
    SortedSet<V> removeAll(@Nullable Object key);

    /**
     * Stores a collection of values with the same key, replacing any existing values for that key.
     *
     * <p>
     * Because a {@code SortedSetMultimap} has unique sorted values for a given key, this method
     * returns a {@link SortedSet}, instead of the {@link java.util.Collection} specified in the
     * {@link Multimap} interface.
     *
     * <p>
     * Any duplicates in {@code values} will be stored in the multimap once.
     */
    @CanIgnoreReturnValue
    @Override
    SortedSet<V> replaceValues(K key, Iterable<? extends V> values);

    /**
     * Returns a map view that associates each key with the corresponding values in the multimap.
     * Changes to the returned map, such as element removal, will update the underlying multimap.
     * The map does not support {@code setValue()} on its entries, {@code put}, or {@code putAll}.
     *
     * <p>
     * When passed a key that is present in the map, {@code
     * asMap().get(Object)} has the same behavior as {@link #get}, returning a live collection. When
     * passed a key that is not present, however, {@code
     * asMap().get(Object)} returns {@code null} instead of an empty collection.
     *
     * <p>
     * <b>Note:</b> The returned map's values are guaranteed to be of type {@link SortedSet}. To
     * obtain this map with the more specific generic type {@code Map<K, SortedSet<V>>}, call
     * {@link Multimaps#asMap(SortedSetMultimap)} instead.
     */
    @Override
    Map<K, Collection<V>> asMap();

    /**
     * Returns the comparator that orders the multimap values, with {@code null} indicating that
     * natural ordering is used.
     */
    Comparator<? super V> valueComparator();
}
